Criminal investigation is an important part of public security work, and the criminal investigation department is a full-time department to crack down on criminal offences. According to the Criminal Procedure Law, criminal investigation is the primary link of criminal proceedings, and the stages of investigation, prosecution and trial are juxtaposed, which is an independent litigation stage. The main evidence for prosecuting criminal suspects in criminal proceedings comes from investigation. The power of investigation, procuratorial power and judicial power shall be exercised by public security, procuratorial and court organs within the scope prescribed by law, and shall not exceed their duties or substitute for each other.
According to the law, the duties of criminal investigators include finding out the category and nature of cases, deciding when to enter criminal proceedings, collecting evidence materials, arresting or controlling criminal suspects, recovering stolen money and goods, protecting innocent people from criminal investigation, ensuring the safety of witnesses and victims, deciding whether to transfer cases to procuratorial organs, and preventing crimes. Specifically, there are: the right to file a case, the right to investigate and inquire, the right to apply for criminal identification, the right to criminal identification, the right to execute criminal compulsory measures, the right to interrogate criminal suspects, the right to conduct on-site inspection, the right to execute seized goods, the right to execute wanted orders, the right to organize identification, the right to execute technical reconnaissance, the right to decide to transfer cases, the right to suspend investigation activities, the right to revoke case suggestions, the right to legally use police weapons, and the right to investigate experiments.